Hypodermic syringe



Apmifl 4-, 1950 M. A. BLAKE 2,502,639

HYPODERMIC SYRINGE Filed Feb. 16, 1948 Marv/77 4, fi/a/re IN V EN TOR.

A TTORNE Y Patented Apr. 4, 1950 HYPODERMIC SYRINGE Marvin A. Blake, Dallas, Tex., assignor to American Instrument Corporation, a corporation of Texas Application February 16, 1948, Serial No.'8,719

3 Claims.

This invention relates to hypodermic syringes and more particularly to a syringe in which provision is made for predetermining medicinal dosages to be administered.

The principal object of the invention is to accomplish in a simple and dependable manner that which has hitherto required a more or less complicated mechanism, that is to say, to provide a syringe equipped with a lever disposed in convenient relation to the conventional finger grips by which the syringe barrel is held, so that the said lever may be manipulated from side to side as the plunger is depressed, thereby controlling the latters movement to correspondingly predetermine the quantity of fluid ejected from the syringe barrel. The lever is effective to accomplish the foregoing through the provision of a plurality of columns of notches in the plunger, the notches of one column being staggered in relation to the notches of another column, said notches receiving a spring pressed detent retained in a disc-like member rotatably embracing the nonrotatable plunger and actuated by said lever to change the position of the detent with respect to notches of alternate columns-thus to permit displacement of the plunger a distance equal to the spaces between the notches.

' Another object of the invention is to provide a dosage predetermining means for hypodermic syringes of such design and construction that accidental overdosage is not possible and further, the control mechanism can be employed equally as well in darkness as in light. Moreover, when not needed, the mechanism may be quickly rendered inoperative to convert the syringe to conventional use.

Still another object of the invention is to provide a dosage control mechanism for hypodermic syringes which will in no wise interfere with fill ing the barrel and evacuating air therefrom, this being done with the mechanism in neutral position, allowing free and unrestricted movement of the plunger.

With the foregoing and other objects in view, the invention has further reference to certain features of accomplishment which will become apparent as the description proceeds, taken in connection with the accompanying drawing wherein:v

Figure 1 is a side elevational view of a hypodermic syringe constructed according to the invention.

Figure 2 is a side elevational view showing per se a modified form of plunger which is interchangeable with a plunger having a more or less number of notches therein.

Figure 3 is a view of the syringe shown in Figure 1 in vertical section, and

Figure 4 is a view in transverse section on a larger scale, taken on line 4-4 of Figure 3.

Continuing with a more detailed description of the drawing, reference numeral I0 denotes a cylindrical shell adapted to enclose and protect the glass ampule or barrel I I of the syringe, into which is drawn the desired medicinal fluid through a conventional hypodermic needle not shown, attached to the inlet I2 of the syringe. Openings I3 in the shell l0 provide visibility to determine the amount of fluid in the barrel.

Slidable in the barrel II is a piston I4 which is actuated by a plunger rod I5, encased in a plunger tube IS. The plunger elements are assembled by first placing the rubber washers of the piston I4 on the rod I5 so that they will rest on the disc I! afiixed to the end of the rod. The tube I6 is then slid onto the rod so that its lower end will bear against the uppermost of the piston washers. Finally a knob I8 is threaded onto the upper end of the rod I5.

The upper end of the shell I!) is exteriorly threaded to receive first, a knurled ring I9, followed by a transverse finger grip 20 and finally, a cap 2 I.

Within the shell III at its bottom is disposed a sealing washer 22 against which bears the lower end of the barrel I I. The upper end of the barrel is sealed by a rubber washer 23 which is held in place by pressure of the cap 2| bearing against the dosage control mechanism enclosed in the cap and to which further reference will be made presently in detail.

It will be observed that the tube I6 has a longitudinal flat 24 on one side thereof which corresponds to a flat segment of the aperture in the cap 2| through which the plunger reciprocates. This arrangement insures that the plunger will be constrained against other than reciprocative displacement with respect to the syringe body. The flattened portion 24 of the tube possesses the other characteristic of providing a neutral position for the dosage control mechanism, to become apparent presently.

Centered approximately apart on the plunger tube It are two columns or longitudinal rows of recesses or notches 25. The relative spacing between the notches of one row and those of the companion row determines the quantity of fluid which will be ejected by the piston I4 from the barrel II, such spacing being predetermined according to the cubic inch capacity of the barrel.

To control the effective displacement of the plunger, a disc 26 is arranged in the cap 2| and is centrally apertured to receive the plunger, provision being made to accommodate the flat 24 of the tube 16 so that the plunger will not rotate in the disc. An annular groove 21 is made in the periphery of the disc 26 and disposed in this groove is a spring ring'28, the ends-thereof being anchored in recesses 28, as shown in Figure 4, yet allowing for limited expansion of the spring. A semi-circular element 29 lies within theconfines of the spring ring 28 in a recess made 'in'the disc 26 opposite the anchorage ofithespring. Theflat area of the element is adapted to bear, under tension of the spring 28, against the surface of the plunger which latter includes the tube 16 containing the notches 25. Since only the disc 26 is rotatable in relation to the plunger and syringe body, the element 29 may change position with respect 'to the two-columnsof notches 25 only by oscillating the disc 26. This is accomplished by the .lrnob or lever 80 whose stem is connected to the periphery of the disc 25 andprotrudes through a slot 3] in the wall of the cap.

As "the disc 26 is rotated, the element 29 rides out of a retaining notch 25-onto the commonsurface of the plunger against .the constricting action of the spring 28 :and is disposed between opposing notches 25 of the companion row of notches. Thumb pressure on the :knob I8 will depress the plunger :until the next succeeding notch 25is brought into a position to receive the element 29. Thus, the degree of travel of the plunger the distance equal to half the distance betweenthe notches of one row determines the quantity of fluid ejected from the syringe by the piston l4. Should it be desired to administeran equaldosage, the control lever 30 is shifted to the opposite extreme and the plunger further depressed. By counting the number of times the lever 30 is moved from side to :side, the user is apprised of the .quantity of medicine administered-of even larger doses.

The slot 3! in which the lever 30 is oscillated has a recess 32 at each end thereof and a recess 33 midway between its ends. The end recesses 32 prevent too free movement of the lever 30 from extreme positions thereof and serve to indicate to the user the position of the disc. The intermediate notch 33 is adapted to retain the element 129 in register with the longitudinal flattened portion 24 of the plunger or in neutral position. When so disposed, the element will not interfere with free and unrestricted movement of the plunger such as when refilling the barrel l I or in cases when the .dosage constitutes theentire contents of the syringe.

In Figure 2 is shown .a plunger in which the notches of each row are spaced more closelyxthan in Figures 1 and 3. It is a simple .matter to substitute plungers or the notched sleeves when changes in quantity of medicine to be administered are indicated.

Manifestly, the construction as shown and described is capable of some modification and such modification as may be construed to fall within the scope and meaning of the appended claims is .also considered to be within the spirit ahdiintent :of the invention.

What is claimed is:

1. A hypodermic syringe including a barrel and a plunger having an interchangeable sleeve thereon, the latter having a longitudinal flattened portion and two parallel and longitudinal rows of notches therein, the notches of one row being staggered in relation to the notches of the companion row, a cap on said barrel apertured to coniormably reeeivecsaid plunger sleeve to hold said plunger against other than reciprocative movement with respect to said barrel, a disc rotatable in said cap, a spring retained element in said disc, means for oscillating said disc to alternately align said element with the notches of -.said.rows to thereby limit the degree of longitudinaldisplacement of said plunger and means for retarding movement of said latter means at each extreme position and, at an intermediate position, for aligning said element with the flattened :portion of said sleeve to release said plunger for unrestricted longitudinal displacement.

.2. A hypodermicsyringe including a barrel and a plunger, an interchangeable sleeve on said plunger having staggered notches arranged longitudinally therein and held with said plunger against rotative displacement with respect .to .said barrel, a disc rotatably mounted on said plunger through which the latter is adapted to reciprocate,.a cap enclosing said disc and having-a slot therein, .a. spring pressed element in said disc, :2. control lever attached to said disc'andextending .through the slot of said-cap for oscillating the disc to dispose said element in alternate alignment with said notches to limit longitudinal displacement of said plunger and means for releasing said plunger for unrestricted longitudinal movement.

.3. In .a hypodermic syringe, a barrel and plunger, .a sleeve .on said plunger having longitudinally staggered notches therein, means for holding said sleeve and plunger against other than longitudinal displacement with respect to said barrel, a cap .non-rotatably mounted on the plunger having a slot in one side thereof, a centrally apertured disc rotatable in said cap having aperipheral groove, .an element .in said disc and a spring lying in said groove to bear against and urge said element toward the aperture of said disc and against the sleeve of said plunger slidable .in said aperture for alternate alignment with said notches to limit longitudinal displacement of said plunger and topredetermine the quantity-of fluid expelled from said barrel.

MARVIN A. BLAKE.

REFERENCES CITED The following references are of record in the file .of this patent:

UNITED STATES PATENTS Number Name Date 1,393,720 Lomas et al Oct. 1-1,, 1921 2,316,095 Mead, Jr. Apr. 6, 1943 2,369,304 Lewis Feb. 16, 1945 2373520 Wallin Apr. 10, 1945 2,409,656 Austin Oct. 22, 1946 FOREIGN PATENTS Number Country Date 686,202 Germany Jan. .5, 1940 

